1. The number of ELECTRONS identifies whether an atom carries a charge as an ion or is neutral.
2. The number of PROTONS identifies the type of element.
The number of each type of subatomic particle plays an important role in the characteristics of the atom. The general element classification (hydrogen, carbon, oxygen, etc.) is governed by the number of protons in the nucleus. If the number of protons changes in an atom, so does the type of element. The electrons are the only type of subatomic particle not in the nucleus. They orbit around the nucleus, bound by the electromagnetic force. When electrons are lost or gained by a neutral atom, the charge balance shifts, resulting in the atom becoming an ion. Ions can be either positive when electrons are lost or negative when electrons are gained.